1. Field of the Invention
This invention relates to a portable heat sealing apparatus for plastic bags and more particularly, relates to an improved more efficient heat sealing apparatus.
2. Background Information
Plastic bags are sealed by heating the perimeter at the opening to the bag. Heat is applied across the opening, under pressure that melts the plastic and "welds" the opening of the plastic bag. There are plastic bag heat sealers that include drawing a vacuuming then sealing the opening by applying heat to melt and weld the opening together. These devices are complicated and expensive, and have jaws that are heated to melt the plastic bag opening after a vacuum has been drawn in the bag.
There is also a plastic bag heater disclosed and described in U.S. patent application Ser. No. 3,236,174 issued Feb. 22, 1966 to Hutchinson et al, one of whom is the inventor of the invention disclosed herein. This patent discloses a portable plastic bag sealer that has a sealing edge with controlled heat to seal the plastic bag my applying pressure against the opening of the plastic bag with the bag positioned on a surface. The device disclosed is simple in construction and use, and can be operated by one hand of an operator. It provides superior seals to comparable portable apparatus that were previously available.
However this device is somewhat thermally inefficient and can have some exposed outer hot surfaces as are typically exposed in the use of hot cloth irons. The heater is in the form of a T-bar that is heated by ceramic heating elements on either end. The heating elements must generate a considerable amount of heat energy to heat the entire T-bar to attain sufficient high temperature on the heating edge to seal the plastic bag. This results in the entire portable bag sealer becoming hot enough to degrade internal components and thus, shorten the sealers operating life. In addition, the inefficient heater requires substantial power to generate sufficient heat to seal a plastic bag.
It is therefore, one object of the present invention to provide an improved plastic bag sealer that provides more efficient heating of the sealing edge.
Yet another object of the present invention is to provide a plastic bag sealer having an improved heater that provides more uniform heat at lower power inputs.
Still another object of the present invention is to provide a plastic bag sealing apparatus, which reduces heat loss by preventing heat transfer to surrounding components and the surrounding atmosphere.
Still another object of the present invention is to provide a plastic bag sealing apparatus that allows small gauge insulation wire to be used that is less expensive and lasts longer when used at the reduced temperatures.
Yet another object of the present invention is to provide an improved plastic bag sealer having an improved heater that prevents transfer of heat to external components (e.g., the cover) thereby providing a safer sealer.
Yet another object of the present invention is to provide an improved plastic bag sealing apparatus with an improved heater that prevents insulating plastic parts from breaking down due to high operating temperatures.
Still another object of the present invention is to provide a plastic bag sealer having a silicon rubberized heater with embedded heater wires that are clamped in place by insulating plates alone or in conjunction with fiberglass insulation.
Still another object of the present invention is to provide a plastic bag sealing apparatus having an improved heater that provides greater heat transfer to the T-bar edge, and less heat transferred to structural components.
Yet another object of the present invention is to provide a plastic bag sealing apparatus having an improved flat silicon sheet heater having embedded heating wires that provide uniform heating over the entire length and width of the T-bar heater.
Yet another object of the present invention is to provide an improved plastic bag sealer having an improved heater utilizing thermally insulating standoffs that assists in reducing transfer of heat to surrounding components and external surfaces.
Still another object of the present invention is to provide a plastic bag sealing apparatus having an improved tubular rod heater. The improved heater will deliver uniform heat energy concentrated in the immediate area of the "T-bar" sealing edge. The rod heater design reduces the required input heat and further reduces heat energy loss to surrounding components and atmosphere.
Still another object of the present invention is to provide an improved hand-held plastic bag sealer having improved long life elastic foam support springs for resiliently supporting an elongate T-shaped heater.
Yet another object of the present invention is to provide an improved hand-held plastic bag sealer having integrally formed thermally insulating standoffs on a heater clamping plate.